Why does the sun lighten our hair, but darken our skin?

Question: Why does the sun lighten our hair, but darken our skin?
- Keywords:
  darken,
  lighten,
  skin,
  sun
Asked by finlay to Cathal, Daphne, Darren, Jon, Katherine on 15 Mar 2012. This question was also asked by spongebob48.
- Katherine Haxton answered on 15 Mar 2012:
  
  The sun destroys some of the pigments in hair called melanin and because hair is dead, it can’t be remade. The sunlight does the same thing as hair bleach. Skin is very much alive and the sunlight makes it produce mroe melanin which causes it to go dark as protection against the sun.

Question: Why does the sun lighten our hair, but darken our skin?